in a 3ft tank you're really going to find how much water gyres can move. the lunar tidal mode and oceanic gyre modes both create strong flow but I found when they simulate the tide rolling in and out it completely shifted the substrate in my tank, sometime onto corals even at the lowest setting.
in the end I actually did 6 custom 4-hour programs which I found in owners manual as an example. it allowed me to tune the strength down where I needed it and best of all, I gained familiarity with the controller and learned how to adjust it.
one thing to definitely be aware of is that the blades are marked "A" and "B" which matters as one is stronger when rotating forward and the other backward. I just played around with them until I found what best suited my set-up and I always make sure assemble them the same way when I clean.
